These patrons of upscale suburban commerce are a marketer’s dream. But suburban and exurban areas like this also are increasingly rich targets for political gain — including in Minnesota’s 3rd Congressional District, where a lively race for an open seat will take place next year.

Long firmly in the Republican column, the tony neighborhoods on the borders of major American cities have become key battlegrounds in the 2008 cycle. It is a fight that beleaguered Republicans are being forced to contend with.

Suburban and exurban areas like this were central to Republican political guru Karl Rove’s grand scheme for cementing GOP dominance for decades in the wake of President Bush’s 2004 reelection victory.

Concerned about their families’ safety after the Sept. 11, 2001, terrorist attacks, wary of tax increases proposed by Democrats on middle- and upper-income workers and skeptical of judicial rulings allowing gay marriage and other sweeping social changes, suburban and exurban districts in places like Columbus, Ohio, and Fairfax, Va., lent crucial support to the Bush-Cheney ticket. Rove boasted often of his intent to lock in that trend and turn the once-purple turf into a rich red hue.

But in 2006, things changed: Democrats won the congressional vote in the nation’s 50 biggest metropolitan areas by making large gains in what were once Republican-leaning suburbs, according to research by Ruy Teixeira, a joint fellow at the Center for American Progress and the Century Foundation.

In emerging suburbs — considered a step closer to cities than exurbs — the Democratic vote in 2006 reached nearly 45 percent, several points higher than in 2002, when it was below 40 percent. And there were big Democratic gains in the exurbs, as well, as the Democratic vote share jumped from 36 percent in 2002 to 42 percent in 2006.

The trend is likely to continue in 2008, as Democrats seek to protect the House majority they won in 2006. More than half of the 17 GOP House members who have announced their retirements — including Rep. Jim Ramstad from Minnesota’s 3rd District — are moderates from suburban districts who were facing increasingly difficult reelection runs.

Voters in the suburbs and exurbs, swayed less by political dogma and ideology than by competence and good government, seemed repelled by the performance of the Bush administration and the GOP-led Congress, as well as the rising clout of conservatives in Republican circles in Washington.

“They’re people who are concerned about transportation, people who are concerned about health care and education,” Teixeira said. “They don’t see every problem as being solved by low taxes. The fast growth rate is turning these places less conservative.”

The same dynamic is playing out here in the 3rd District. In 2004, the district backed Bush over John F. Kerry by 51 percent to 48 percent — the exact inverse of Minnesota’s statewide vote.

But now that the district is coming open in 2008, due to Ramstad’s retirement, the race is likely to be a toss-up between Republican state Rep. Erik Paulsen and state Sen. Terri Bonoff, the likely nominee of the Democratic Party (or DFL, for Democratic-Farmer-Labor Party, as it is officially known in Minnesota). The contest’s closeness is a testament to the district’s shifting political terrain and the willingness of suburban and exurban voters to consider Democratic alternatives.

Mike Jorgensen, a 49-year-old lab supervisor at a biotech firm in the Minneapolis suburbs, said he consistently supported Ramstad over the years but would now take a hard look at a Democratic candidate. “Republicans have had their chance, and they deserved to lose,” he said.

Rather than emphasizing ideological wedge issues, Bonoff and Paulsen are following the national script for appealing to suburban and exurban voters. Both are painting themselves as pragmatic problem solvers who can best represent the residents of the 3rd District, where professional workers are plentiful and the median income is $63,816.

Voters in areas like the 3rd District are certainly not liberals — just pragmatic, and, above all, they value merit, said Robert E. Lang, an associate professor in urban affairs and planning at Virginia Tech’s School of Planning and International Affairs.

“I don’t think they’re naturally Democrats on issues like taxes and government spending. Yet they belong to this kind of professional, managerial class,” he said, “people whose lives are defined by expertise.”

Republican strategists caution against reading too much into recent Democratic progress in suburbs and exurbs, suggesting that these areas are a long way from slipping into the opposite camp. J. Scott Jennings, who until this fall was deputy director in the White House Office of Political Affairs, said such voters are still amenable to the general Republican message of lower taxes and small government.

“I think they could be reeled in. I think they are probably closer to middle-right on the spectrum than on the left end of the spectrum,” said Jennings, now director of strategic development at Peritus Public Relations in his native Kentucky. “They really are more conservative than they are liberal.”

In Minnesota, Ramstad’s retirement has Democrats salivating at the chance to claim the district, home to the nation’s largest shopping mall, the 4.2 million-square-foot Mall of America in Bloomington. The district is Minnesota’s most affluent, taking in the Hennepin County suburbs north, west and south of Minneapolis.

Candidates from both parties are positioning themselves as natural heirs to the centrist legacy of Ramstad, who never won less than 64 percent of the vote in his nine House elections.

Paulsen, 42, worked for Ramstad before winning election to the state House in 1994.

In the legislature, and now on the congressional campaign trail, Paulsen has steered a moderately conservative course. His top priorities in Congress would include pushing middle-class tax cuts and revising portions of the No Child Left Behind law to make it less bureaucratic and more attuned to local education needs.

Paulsen is quick to stress his bipartisan credentials. “I’ve tried to implement that model at the state level and now want to take it to Congress,” he said.

For her part, Bonoff contends that the suburban district has moved away from Republicans. Bonoff, 50, is in a sense the quintessential suburban soccer mom. She grew up in Edina and worked at several corporations, including Tonka Toys and Toy Soldiers. Wanting to spend more time with her high-school-aged children, she retired in 1999 as a marketing executive at Navarre Corp.

Bonoff ultimately decided to run for office, and in 2005 she won a special election to the state Senate, the first Democratic victory in the legislative district in nearly 20 years.

While a Democratic success story, Bonoff, like Paulsen, stresses moderation in this swing district. She said that U.S. troops in Iraq should be drawn down but that it must be done carefully. Bonoff characterized voters in the district as fiscally prudent and tax sensitive but said they also believe in a social safety net.

Bonoff faces opposition for the DFL endorsement from lawyer and Iraq war veteran J. Ashwin Madia. Edina Mayor Jim Hovland, a lawyer and until recently a Republican, is also considering jumping in. But Bonoff is considered the top recruited candidate for the seat, and the Democratic Congressional Campaign Committee touted her official entry into the race on Nov. 5.

Bonoff believes her message will resonate in the highly educated district. She explains residents’ past support for Republicans this way:

“Maybe they grew up in Minnesota when Hubert Humphrey was there — their parents were Democrats, they grew up hearing those values. And then they became immersed in being a soccer mom and so forth, and they went to the Republican Party. But then it swung so far to the right that they saw Democrats were at the heart of who they are and reflected those values.”

That argument — that moderate Democrats are the best political fit for districts like this one — will be played out in a number of exurban and suburban districts where Republicans face potentially daunting demographic challenges next year.

• Illinois’ 14th District: The trend is particularly on display in this district, represented for almost 21 years by former Republican Rep. Dennis Hastert, the longtime House speaker. He resigned from Congress on Nov. 26, triggering a special election, to be held on Feb. 5, 2008, the same day as the state’s presidential primary.

The district includes the far western suburbs of Chicago and takes in Aurora, now the second-largest city in Illinois. Throughout Hastert’s rise in the Republican congressional ranks in the late 1980s and the 1990s, and during his eight-year speakership, this was a fast-growing — and GOP-leaning — congressional district.

But Aurora and Elgin, another major city in the district, are now about one-third Hispanic, and Hispanics have the potential to be a crucial voting bloc in a closely contested election.

With these shifting demographics, Democrats now have a plausible shot at nabbing the seat. That’s what happened in the neighboring 8th District in Chicago’s prosperous northern suburbs in 2004, when Democrat Melissa L. Bean ousted 35-year Republican incumbent Phil Crane.

In Hastert’s district, a potentially bruising Republican primary is in the works between dairy magnate Jim Oberweis and state Sen. Chris Lauzen. On the Democratic side, wealthy scientist Bill Foster is a front-runner for his party’s nod, though he faces competition in the primary.

• Michigan’s 9th District: Democrats are also eyeing the suburban/exurban vote in Michigan’s 9th District, the state’s wealthiest and best-educated, where Republican Rep. Joseph Knollenberg won only 52 percent of the vote against an underfunded challenger in 2006.

Bush carried the district in 2004 with 50 percent of the vote, and Knollenberg is squaring off against Democrat Gary Peters, a highly touted former state lottery commissioner and state senator.

• Ohio’s 15th District: In 2006, Franklin County Commissioner Mary Jo Kilroy, a Democrat, came painfully close to knocking off seemingly entrenched Republican Rep. Deborah Pryce, 50.1 percent to 49.6 percent. The seven-term congresswoman is retiring next year for family reasons. Republican state Sen. Steve Stivers recently entered the race, setting up a likely showdown with Kilroy.

• New Jersey’s 7th District: Republican Mike Ferguson’s surprise retirement announcement last month has Democrats eyeing this increasingly competitive seat. Democrats already have a highly regarded recruit in state Assemblywoman Linda Stender, who narrowly lost to Ferguson in last year’s election. No GOP front-runner has emerged.